Offset-blanket.



G. R. CORNWALL.

OFFSET BLANKET.

APYLIOATION FILED FEB.4, 1910.

'wmgms, Patented Oct. 7, 1913.

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GEORGE E. CORN WALL, 0F RYE, NEW YORK.

OFFSET-BLANKET.

Specification of Letters Patent.

Patented Get. "7, 1913.

Application filed February 4, 1910. Serial No; 542,104.

To all whom it mag concern Be it known that I, Gnonon R. CORNWALL, a citizen of the United States, residing at Eye, in the county of Westchester and State of New York, have invented new and useful Improvements in Offset-Blankets, of which the following is a specification.

The invention relates to devices and means for oflset printing, that is, printing by which the inked form comes into impression contact with an impression receiving and yielding surface which in turn comes into contact with the surface, such as a sheet of paper, to be imprinted and makes an imprint thereon.

Objects of the invention will in part be set forth hereinafter and will in part be obvious to those skilled in the art.

The invention consists in the novel parts, constructions, articles, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and forming a part hereof, illustrate one embodiment of the invention, the same serving in connection with the description herein to explain the principles of the invention.

Of the drawings: Figure 1 is an elevation of a printing cylinder with an offset printing surface, constructed in accordance with the principles of the invention, carried thereon; Fig. 2 is a plan view of the metal sheet constituting a pait of the offset printing element; Fig. 3 is a section through the blanket shown in Figs. 3 and 6 on a line corresponding to line AB of Fig. 2; and Fig. 4 is a detail on an enlarged scale showing the plate stretching and holding clamp of the cylinder engaging the metal plate to stretch and hold the blanket or the cylinder.

Referring to the accompanying drawin 's, illustrating by way of example one embo iment of the invention, 1 indicates a printing cylinder having a shaft 2 which is journaled on the press frame in a well known manner. Mounted upon the cylinder 1 is an. offset printing element 3. Said offset printing element 3 comprises a relatively thin, flat and flexible metal plate 4 having a plurality of apertures 5 therethrough. A suitable oifset surface 6 extends as a layer over the flexible metal plate 4 and also extends into the apertures 5 in order to hold the offset material in position. Said offset material may be rubber, and may extend in a layer on both sidesof the flexible metal plate 4, if desired.

otally mounted thereon at 19.

In Fig. 3 of the drawings a layer 6 is shown on one side of the metal plate 4, and a layer 7 on the other side, said layers filling and uniting in the apertures 5. The rubber surfaces 6 and 7 are thus not only firmly held With the blanket shown, however, the rubber layer or layers are held or anchored to the metal plate at so many points and so close together as to practically eliminate the creeping, thereby preventing deformation and indistinotness in the printed matter produced from the offset plate or blanket.

Suitable means are provided for holding the ofiset element 3 in position upon the cyl. inder or bed of the press, and in the embodied form thereof ciamps 8 are shown engaging the plate 4. The plate 4, if desired, may be equipped with means for coacting with the clamps 8 to give a firm hold upon the plate 4 and there is shown herein a rod 9 about which the edge of the plate 4 is turned or to which it is fastened. The clamps 8 are mounted on an arm 10 swinging about a bearing 11 mounted on the cylinder 1, the lower jaw 17 being integral with the arm 10 and the upper jaw 18 being piv- Suitable means for the arm 10 are provided to cause it to stretch the plate and for this purpose the stud 12 is threaded through the arm 10 and bears upon the surface 16 on the cylinder 1. Means are also provided for closing the clamping jaws 8 together and are shown herein as a screw threaded rod 13 hearing against the tail 14 of the movable clamping jaw and threaded into the tail 15 of the fixed clamping jaw to press the jaws together upon the rods 9 or plate4 as the case may be.

In making the blanket, the metal plate 4 may be placed in a form with layers of crude rubber on either side thereof. The rubber is then vulcanized and flows together and unites through the apertures in the plate, and also becomes adherent to the sur face of the plate 4. The layers 6 and 7 are brought to a condition which experience has shown to be best adapted for offset printing. The ends of the plate 4 are left projecting at the two sides of the ofiset blanket or plate which lie across the press cylinder and which are engaged by the plate clamps of the cylinder. These edges of the plate may be turned over or the rod 9 placed therein, as already stated, to give the clamps a better hold on the plate. It will be understood. also that a flat bed could be used instead of the cylinder, if desired.

Through the resent invention all danger of straining or destroying the offset surface is obviated, and a uniform stretching or tension throughout the entire extent of the offset printing surface is secured, as well as preventing the creeping of the surface and thereby distorting and throwing out of register, or otherwise impairing the good quality of the printing.

It will be understood that the invention is not limited to the exact forms shown and described, but that variations may be made therefrom within the scope of the accompanying claims.

What I do claim and desire to secure by Letters Patent, is: v

1. In a printing press, the combination with a support for a printing element, of

an offset printing element comprising a unitary flexible plane sheet of non-elastic metal having apertures or perforations therein of relatively small extent, and plane imperforate areas of relatively large extent therebetween and a layer of elastic oftset material constituting a printing surface, said layer being adherent upon and sup orted by said plane imperforate areas an entering into said apertures, whereby said layer of offset material is supported against lateral spreading and deformation and against creeping, said unitary flexible plate extending beyond said elastic offset material to afl'ord a gripping surface for the plate clamps of the press.

2. In a printing press, the combination with a support for a printing element, of an offset printing element comprising a unitary flexible plane sheet of flexible metal having apertures or perforations therein of relatively small extent, and plane imperforate areas of relatively large extent therebetween and a layer of elastic oifset material constituting a printing surface, said layer being adherent upon and supported by said plane imperforate areas ano entering into said apertures, whereby said layer of ofi'set material is supported against lateral spreading and deformation and against creeping.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

GEORGE R. CORNWALL.

\Vitnesses:

JOHN D. MORGAN, Rose MENK. 

